Formation of evoked potentials in cat orbital cortex during prenatal ontogeny.

Studies were done during the antenatal ontogeny of cat fetuses to elucidate the nature of the formation of evoked potentials in the orbital cortex of the brain in response to stimulation of the cervical part of the vagus nerve. The experiments were done under conditions which preserved the placental blood circulation. It has been shown that the first clearly expressed electrical responses in the orbital cortex after stimulation of the cervical part of the vagus nerve arise during the second half of antenatal development. During early stages of intrauterine development (6 weeks) the EP takes the form of slow, negative waves of small amplitude and large latency. During later periods of embryogeny (8-9 weeks of intrauterine life) there is noted a contraction of the latency period and an increase in the amplitude of the negative waves.